Fire protection system with time responsive discharge heads

ABSTRACT

A fire protection system for buildings and the like in which a plurality of extinguishant discharge heads are mounted in an elevated position in the building and are connected to a source of extinguishant. A thermal responsive device is responsive to a fire developing in the building and is adapted to place one or more of the heads in an operable condition for a predetermined time period. The heads that are placed in an operable condition are adapted to be opened in response to a predetermined system condition occuring within the time period.

United States Patent 1 1 1 3,722,597

Friedman 51 Mar. 27, 1973 54 FIRE PROTECTION SYSTEM WITH 3,645,338 21972 Livingston ..1s9 42 TIME RESPONSIVE DISCHARGE 3,599,723 8/1971Vorkapick ..169/42 HEADS 3,587,747 6/1971 Romero et a1 ..l69/42 [75]Inventor: Raymond Friedman, Needham,

Mass. 02062 [73] Assignee: Factory Mutual Research Corporation, Norwood,Mass.

[22] Filed: Aug. 5, 1971 [21] Appl. No.: 169,241

[52] U.S. C1 ..l69/38, 169/42 [51] Int. CI ..A62C 37/08 [58] Field ofSearch ..169/S, 16, 37, 38, 39, 42

[56] References Cited UNITED STATES PATENTS 2,414,127 1/1947 Shaw..l69/38 X 2,568,429 9/1951 Burnam et a1. 2,935,135 5/1960 Granttlr...169/5 Primary Examiner-Lloyd L. King Attorney-Joseph Lane et a1.

[57] ABSTRACT A fire protection system for buildings and the like inwhich a plurality of extinguishant discharge heads are mounted in anelevated position in the building and are connected to a source ofextinguishant. A thermal responsive device is responsive to a firedeveloping in the building and is adapted to place one or more of theheads in an operable condition for a predetermined time period. Theheads that are placed in an operable condition are adapted to be openedin response to a predetermined system condition occuring within the timeperiod.

16 Claims, 6 Drawing Figures PATENTEUHARZ'HQYS v 3 722.597 SHEET 1 or 2r INVENTOR RAYMOND, FRIEDMAN ATTORNEYS PATENTlium-mznms 3.722597 SHEET 2OF 2 FIG. 2.

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INVENTOR RAYMOND FRI EDM AN ATTORNEYS FIRE PROTECTION SYSTEM WITH TIMERESPONSIVE DISCHARGE HEADS BACKGROUND OF THE INVENTION This inventionrelates to a fire protection system, and more particularly, to such asystem employing a plurality of extinguishant discharge heads fordischarging extinguishant towards the fire in the space to be protectedin response to predetermined conditions.

Recent developments in fire protection systems have attempted to solvethe unique fire hazards presented by high-storage enclosures, such aswarehouses, etc., which house very large amounts of materials. Thesematerials, which often include highly inflammable plastics and the like,are often stacked to very high levels and develop very high-challengefires when ignited.

As an example of a type of hazard involved, the fire column, or plume,caused by such fires may exceed twenty feet in height and often flaresout beneath the ceiling of the protected space. The increased heat willactuate numerous discharge heads of a fixed fire protection systeminstalled in the building, some of which are located at such a distancefrom the fire that they are ineffective to deliver the extinguishant tothe fuel surfaces. This contributes not only to redundant and floodinguse of the extinguishant, but, more significantly, robs the headsdirectly over the fire from valuable extinguishant needed to extinguishthe fire.

In US. patent application Ser. No. 106,652, filed on Dec. 23, 1970, byWilliam L. Livingston and assigned to the same assignee as the presentinvention, a fixed fire extinguishing system is disclosed which isdesigned to limit the number of heads which will be activated by fire.This system utilizes heads that are spaced apart relatively longdistances and have relatively large outlet orifices to enable greaterquantities of water or other extinguishant to be delivered from eachhead at lower flow rates. Preferably, the heads are in the form of wideangle spray nozzles which develop a downwardly directed spray havinglarge size droplets as compared to the droplets produced by theconventional sprinkler heads. Each nozzle is adapted to be opened by athermal fuse which is responsive to a predetermined temperature in itsimmediate vicinity.

With this arrangement, the first nozzle actuated by the fire has a muchbetter possibility of extinguishing the fire, because of the increasedability of the larger droplets to penetrate the fire plume of a highchallenge fire. If the heat of the fire spreads, additional nozzles areactuated to help the first nozzle fight the fire and to wet down areassurrounding the fire to provide exposure protection to inhibit thespread of the fire. However, the additional nozzles which are allowed tobe actuated are limited to a small number to avoid the problemsdiscussed above. This is achieved by establishing a pressure fioor sothat a minimum pressure must exist at each nozzle before it will open,with the system being designed so that this minimum pressure will not bereached until a predetermined number of nozzles have been actuated.

Although this embodiment results in several advantages includingincreased fire fighting capability and significant cost savings inseveral respects, it suffers from one disadvantage. Specifically, inestablishing the above-mentioned pressure floor, an expellable plugnormally blocks the outlet of the nozzle and is adapted to be expelledfrom the nozzle to permit extinguishant flow therethrough upon thefusing of a conventional temperature responsive device and the presenceof a fluid pressure in the nozzle of a magnitude exceeding apredetermined value. In establishing the latter value, a connecter,preferably in the form of a thread, is utilized to retain the expellableplug in a closed position. The design is such that the extinguishantpressure in the nozzle places the thread in tension and must be of avalue to break the thread before the expellable plug can be released.

Although providing the several advantages emphasized above, it wassubsequently discovered that this pressure floor design could bedefeated by delayed increases in the pressure of the system. Inparticular, assuming that the thermal fuses of a number of nozzlesrespond to a fire and actuate the nozzles, the pressure floor oftenoperates to prevent a portion of the nozzles from being opened as aresult of an inadequate pressure existing at the latter nozzles.However, if at some period of time after this, the system-pressurerises, such as, for example, by the addition of an auxiliary watersupply supplied by a fire department or by activating an additionalpump, the resulting increase in water supply pressure will then enablesome or all of the additional fused nozzles to open. However there maybe no fire under these nozzles, with three undesirable consequences: (l)failure to take advantage of the higher pressure to deliver more waterto the previously opened nozzles over the fire; (2) increased rate ofdepletion of the water reservoir, if one is being used; and (3)increased water damage. Even more serious, if the strengthening of thewater supply is only of a short duration, and the supply later revertsback to its original condition because of a tactical decision of thefire department, a mechanical failure, a mistake, or any other reason,then the increased number of nozzles remain open at a pressuresignificantly lower than the the original pressure floor, which may notprovide adequate water to suppress the fire. Obviously, this is adeterrent to the fire fighting capability of the system.

SUMMARY OF THE INVENTION It is therefore an object of the presentinvention to provide a fire protection system and discharge head for usein the system, which utilize a pressure floor of the above type, butwhich eliminate a premature defeating of the pressure floor and theresultant opening of too many discharge heads.

Towards the fulfillment of this and other objects, the fire protectionsystem of the present invention comprises a plurality of extinguishantdischarge heads located in a space to be protected, means for connectingsaid heads to a source of extinguishant, means responsive to a firedeveloping in said space for placing at least one of said heads in anoperable condition for a predetermined time period, and control meansfor opening said heads placed in said operable condition in response toa predetermined extinguishant pressure.

BRIEF DESCRIPTION OF THE DRAWINGS Reference is now made to theaccompanying drawings for a better understanding of the nature andobjects of the present invention. The drawings illustrate the best modepresently contemplated for carrying out the objects of the invention andare not to be construed as restrictions or limitations on its scope. Inthe drawings:

FIG. 1 is a schematic, perspective view of a building incorporating thefire protection system of the present invention;

FIG. 2 is a vertical cross-sectional view of a nozzle utilized in thesystem of the present invention;

FIG. 3 is an enlarged partial view similar to FIG. 1, and showing adetail of the nozzle utilized in the system of the present invention;and

FIGS. 4A-4B are partial plan views showing the latching mechanism of thenozzle of FIGS. 2 and 3 in various stages of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a buildingis shown in phantom lines which is equipped with a fire protectionsystem embodying features of the present invention. The system comprisesa feed main 2 connected to a municipal water supply line 4 fordelivering an extinguishant, which in this example is water, to a riser6. The riser 6 is connected to a cross main 8 which, in turn, isconnected to a plurality of branch lines 9.

Each branch line has a plurality of nozzle heads which are operatedautomatically in response to a fire, as will be described, to deliver adownwardly directed spray of water droplets on the fire. The feed main 2extends beyond the riser 6 and can be connected to risers of otherbuildings or, in the case of a large building, to other risers in thesame building. The cross main 8 and the branch lines 9 are suspendednear the ceiling of the building in a conventional manner, and theconnections between the various pipes of the system are also made in aconventional manner.

A nozzle 10 is shown in detail in FIGS. 2 4 and comprises a cylindricalbody 12- having an upper end portion which is internally threaded asshown at 14 for connection to a source of extinguishant, and a lower endportion which defines an outlet orifice 16 of a reduced cross-section. Apair of spiral vanes 18a and 1812 are fixed within the body 12 forimparting a swirling motion to water flowing downwardly therethrough ina conventional manner. The vanes 18d and 18!: support a hollow centralhub 20 which, in turn, slidably supports a rod 22 having a piston head24 fixed on its lower end.

A pair of sealing rings 26 and 28 are positioned about the periphery ofthe head 22 and sealingly engage the inner wall of the body 12 near theoutlet orifice 16. A fusible nut 30 is located in the outlet orifice 26adjacent the plug 24, to provide a safeguard against premature expulsionof the rod 22, and to prevent an accumulation of dirt and grime in theoutlet orifice which might otherwise affect the expulsion of the plug inthe event of fire.

The rod 22 is latched in the position shown in FIG. 2 by a rod 32 whichextends slidably through an externally threaded boss 34 projecting fromthe side of the body 12. The assembly for achieving the latching will bedescribed in detail later.

A sleeve 38 is threaded on the end of the boss 34. The outer end of thesleeve is closed off by an externally threaded stub shaft 40 having aring or yoke 42 thereon. The rod 32 slidably extends through the stubshaft 40, and the other end of the rod engages a conventional thermalfuse element 44 positioned within the ring 42. The fuse element preventsmovement of the rod 32 to the right as viewed in FIG. 2, until the heatof a fire fuses the element 44 so that it collapses. Since the element44 is the standard type commonly used in conventional sprinkler headsnow on the market, it will not be described in greater detail.

The rod 32 has a piston head 46 mounted thereon which slidably engagesthe internal wall of the sleeve 38. A spring 48 is positioned betweenthe boss 34 and the piston head 46 to bias the piston head and the rod32 to the right with a predetermined biasing force. A plate 50 isdisposed in the sleeve 38 and divides the space between the piston head46 and the stub shaft 40 into two chambers 52 and 54, with the chamber52 containing a viscous fluid and the chamber 54 contain-' ing onlyatmospheric air that is trapped therein. An opening 56 extends throughthe plate 50 for receiving the rod 32 with a slight clearance to permitpassage of the fluid from the chamber 52 into the chamber 54 uponmovement of the piston head 46 to the right.

With this arrangement, the piston head 46 and the rod 32 will be drivento the right under the action of the spring 48 upon the fuse element 44collapsing in response to the heat of the fire. This movement will bedampened by the fluid passing from the chamber 52, through therestricted opening 56, and into the chamber 54, with the size of thelatter chamber being selected so that the force resulting from thecompression of the air therein is readily overcome by the force of thespring 48.

As better shown in FIG. 3 a thread 58 is provided which has one endfastened to the upper end of the rod 22. The thread 58 extends throughan opening 59 formed through an end portion of the hub 20 extendingabove the vane 18a, and the otherend of the thread is fastened to thelatter end. The above-mentioned fastening maybe achieved in anyconventional manner, such as by the use of epoxy or the like. The threadis preferably of a nylon material and its length is selected so that itwill have a slight slack therein in the deactivated position of FIG. 2to avoid any unwanted tension being placed thereon due toslightdimensional variations of the other components of the nozzle.

The assembly for latching the rod 22 in the position shown in FIG. 2 isbetter shown with reference to FIGS. 3 and 4. In particular, the rod 32extends through two slots formed in diametrically opposite walls of theportion of the hub 20 extending above the upper plane of the vane member18a. The portion of the rod 32 extending within the hub 20 is enlargedas shown at 60 and has a generally elliptical slot 62 formed therein. Apair of inwardly directed tabs 64a and 64b are formed on the enlargedportion 60 of the rod 32 and are disposed at opposite ends of the slot62. The rod 22 has an enlarged head 66 of a circular shape which is of adiameter slightly less than the distance between the ends of the tabs64a and 64b.

In the normal latched position of FIGS. 2, 3, and 4A, the head 66 isretained in the position shown by means of the tab 64b extendingunderneath the head 66, thereby preventing a release of the latter andtherefore the rod 22.

However, upon movement of the rod 32 to the right as viewed in thedrawings, the enlarged portion 60 of the rod 32 will move relative tothe head 66 and permit the latter to clear the tabs 64b and 64a and thusrelease the rod 22. On further movement of the rod 32, and therefore theenlarged portion 60, to the right, the assembly will attain the positionshown in FIG. 4C, with the tab 64 a extending underneath the head 66 ofthe rod 22. In this position, as in the position of FIG. 4A, the head66, and therefore the rod 22, is latched in the position shown in FIG.2.

In operation, the nozzle is installed at an elevated position in thestructure to be protected in the condition shown in FIGS. 2, 3, and 4A,i.e., with the rod 22 latched in the body member by virtue of the tab64b extending underneath the head 66, and with the thread 58 fixedto-the rod 22 and the upper end of the hub 20. If both the fusible link44 and the fusible link nut 30 are thermally actuated in response to anelevated temperature in their vicinity, the tension of the spring 48will cause the piston head 46 to move to the right as viewed in FIG. 2,with this movement being dampened by virtue of the fluid moving from thechamber 52, through the restricted orifice 56, and into the chamber 54.An initial portion of this movement enables the enlarged portion 60 ofthe rod 32 to attain the positive relative to the head 66 of the rod 22shown in FIG. 4B, and thus free the rod 22 for discharge from the bodymember 12. At this point, the pressure of the extinguishant in the bodymember 12 acts on the inner face of the plug 24 and forces it downwardlyto cause a tension to be applied to the thread 58 in direct proportionto the amount of the pressure. If this pressure is sufficient to breakthe thread, the rod 22 will be completely released and therefore it,along with the plug member 24, will be discharged outwardly from thebody member 12 by the force of the extinguishant pressure. Of course, ifthe extinguishant pressure is not sufficient to break the thread 58, theplug 24 will not be expelled from the body portion 12 despite release ofthe fuse element 44 and the fusible nut 30.

After a predetermined time delay the rod 32, in continuing its movementto the right, will cause the enlarged portion 60 to attain the positionshown in FIG. 4C, with the tab 64a extending underneath the head 66 ofthe rod 22. At this point the rod 22, and therefore the plug 24, will belatched relative to the body member 12 no matter what value the pressureof the extinguishant in the body member attains.

It can be appreciated from the foregoing that the above arrangementpermits the plug 24 to be discharged from the body member 12 in responseto a predetermined extinguishant pressure existing in the body member 12only for a predetermined time period after the actuation of the thermallink 44 and the fusible nut 30. As emphasized above, this eliminates thepossibility of the opening of a nozzle or nozzles by virtue of atemporary delayed increase in the extinguishant pressure available tothe system. The above arrangement eliminates unnecessary water damage,and prevents the critical nozzles nearest the fire from being robbed ofextinguishant as a result of an excessive number of nozzles beingactuated at points remote from the fire in response to a temporaryincrease in the system pressure.

Of course, other variations of the specific construction and arrangementof the time responsive pressure floor for fire protection systemsdisclosed above can be made by those skilled in the art withoutdeparting from the invention as defined in the appendedclaims.

I claim:

l. A fire protection system for buildings and the like comprising aplurality of extinguishant discharge heads located in a space to beprotected, means for connecting said heads to a source of extinguishant,a fusible member for each of said heads for normally retaining said headclosed, said fusible member being responsive to a predeterminedtemperature in said space for conditioning said head for opening, andcontrol means for each of said heads for opening said head in responseto the extinguishant pressure at said head exceeding a predeterminedminimum value during a predetermined time period after said head hasbeen conditioned by said fusible member, said control means maintainingclosed those heads whichare not opened during said time periodirrespective of the extinguishant pressure at said latter heads.

2. The system of claim 1 wherein end of said head includes a closuremember normally preventing the flow of extinguishant through the head,said head opening on the discharge of said closure member from saidhead, and wherein said control means further comprises a spring loadedrod connecting said fusible member and said closure member andadapted-to move relative to said closure member upon the fusing of saidfusible member.

3. The system of claim 2 wherein said rod includes latching meansadapted to latch said closure member to said head prior to the fusing ofsaid fusible means and adapted to release said closure member upon apredetermined movement of said rod.

4. The system of claim 3 wherein said latching means is further adaptedto latch said closure member to said head after an additionalpredetermined movement of said rod in the absence of said predeterminedminimum pressure at said head, the total movement of said rodcorresponding to said time delay.

5. The system of claim 4 wherein said control means further comprisesmeans to dampen said movement.

6. In combination, an extinguishant dispersing head for an automaticsprinkler system for protecting a building, fire responsive means forconditioning said head for opening in response to information receivedfrom a fire in said space, and control means for opening said head inresponse to the extinguishant pressure at said head exceeding apredetermined value within a predetermined time period after the headhas been conditioned by said fire responsive means, said control meansmaintaining said head closed irrespective of information received fromsaid system if it is not opened during said time delay.

7 The system of claim 6 wherein said fire responsive means comprises afusible member for said head normally retaining said head closed andresponsive to a predetermined temperature for activating said controlmeans and initiating said time delay.

8. The system of claim 7 wherein said control means comprises means forsaid head which, when activated by said fusible member, maintains saidhead closed it the pressure at said head is below said predeterminedminimum pressure and opens said head if the pressure at said headexceeds said predetermined minimum pressure during said time delay, andmeans to maintain said head closed after said time delay irrespective ofthe pressure at said head if' it has not opened during said time delay.

9. The system of claim 7 wherein each of said heads includes a closuremember normally preventing the flow of extinguishant through the head,said head opening on the discharge of said closure member from saidhead, and wherein said control means comprises a spring loaded rodconnecting said fusible member and said closure member and adapted tomove relative to said closure member upon the fusing of said fusiblemember.

10. The system of claim 9 wherein said rod includes latching meansadapted to latch said closure member to said head prior to the fusing ofsaid fusible means and adapted to release said closure member upon apredetermined movement of said rod.

11. The system of claim 10 wherein said latching means is furtheradapted to latch said closure member to said head after an additionalpredetermined movement of said rod in the absence of said predeterminedminimum pressure at said head, the total movement of said rodcorresponding to said time delay.

12. The system of claim 11 wherein said control means further comprisesmeans to dampen said movement.

13. In combination, an extinguishant dispersing head for an automaticsprinkler system for protecting a building, fire responsive means forconditioning said head for opening in response to information receivedfrom a fire in said space, and control means for controlling the openingof said conditioned head in response to information received from thesystem within a predetermined time delay after the head has beenconditioned by said fire responsive means, said control meansmaintaining said head closed irrespective of information received fromsaid system if it is not opened during said time delay, said head havingan inlet adapted to be connected to a source of the extinguishant, anoutlet for spraying the extinguishant on a fire and a closure memberpositioned between said inlet and outlet for preventing extinguishantflow through said outlet, said control means comprising latch meanshaving a first deactivated condition, an activated condition and asecond deactivated condition, said control means locking said closuremember in its closed position in said head in said first deactivatedcondition, said control means automatically placing itself in saidsecond deactivated condition within a predetermined time period afterthe initiation of said activated condition, said control means in saidactivated condition controlling said closure member for openingautomatically if the extinguishant pressure in said head exceeds apredetermined minimum pressure, said control means in said seconddeactivated condition locking said closure member in its closed positionirrespective of the extinguishant pressure in said head if the closuremember has not been opened during said activated condition, said fireresponsive means normally maintaining said control means in saiddeactivated condition and placing said control means in said activatedcondition in response to information received from a fire in said space.

14. A fire protec ion system for buildings and the like comprising aplurality of extinguishant discharge heads located in a space to beprotected, means for connecting said heads to a source of extinguishant,fire responsive means responsive to a fire developing in said space forconditioning said heads for opening in a sequence dictated byinformation received from the tire, and pressure responsive means foropening said conditioned heads in response to the existence of apredetermined extinguishant pressure in said system within apredetermined time period after each head has been conditioned by saidfire responsive means, said pressure responsive means maintaining closedthose heads which are not opened during said time period irrespective ofthe extinguishant pressure in said system.

15. The system as defined in claim 14 wherein said pressure responsivemeans is responsive to the extinguishant pressure at each of said headsduring said time delay, said pressure responsive means opening each headif the pressure is greater than a predetermined minimum pressure duringsaid time delay.

16. The system of claim 15 wherein said fire responsive means comprisesa fusible member for each of said heads normally retaining said headclosed and responsive to a predetermined temperature for activating saidpressure responsive means and initiating said time delay.

1. A fire protection system for buildings and the like comprising aplurality of extinguishant discharge heads located in a space to beprotected, means for connecting said heads to a source of extinguishant,a fusible member for each of said heads for normally retaining said headclosed, said fusible member being responsive to a predeterminedtemperature in said space for conditioning said head for opening, andcontrol means for each of said heads for opening said head in responseto the extinguishant pressure at said head exceeding a predeterminedminimum value during a predetermined time period after said head hasbeen conditioned by said fusible member, said control means maintainingclosed those heads which are not opened during said time periodirrespective of the extinguishant pressure at said latter heads.
 2. Thesystem of claim 1 wherein end of said head includes a closure membernormally preventing the flow of extinguishant through the head, saidhead opening on the discharge of said closure member from said head, andwherein said control means further comprises a spring loaded rodconnecting said fusible member and said closure member and adapted tomove relative to said closure member upon the fusing of said fusiblemember.
 3. The system of claim 2 wherein said rod includes latchingmeans adapted to latch said closure member to said head prior to thefusing of said fusible means and adapted to release said closure memberupon a predetermined movement of said rod.
 4. The system of claim 3wherein said latching means is further adapted to latch said closuremember to said head after an additional predetermined movement of saidrod in the absence of said predetermined minimum pressure at said head,the total movement of said rod corresponding to said time delay.
 5. Thesystem of claim 4 wherein said control means Further comprises means todampen said movement.
 6. In combination, an extinguishant dispersinghead for an automatic sprinkler system for protecting a building, fireresponsive means for conditioning said head for opening in response toinformation received from a fire in said space, and control means foropening said head in response to the extinguishant pressure at said headexceeding a predetermined value within a predetermined time period afterthe head has been conditioned by said fire responsive means, saidcontrol means maintaining said head closed irrespective of informationreceived from said system if it is not opened during said time delay. 7.The system of claim 6 wherein said fire responsive means comprises afusible member for said head normally retaining said head closed andresponsive to a predetermined temperature for activating said controlmeans and initiating said time delay.
 8. The system of claim 7 whereinsaid control means comprises means for said head which, when activatedby said fusible member, maintains said head closed if the pressure atsaid head is below said predetermined minimum pressure and opens saidhead if the pressure at said head exceeds said predetermined minimumpressure during said time delay, and means to maintain said head closedafter said time delay irrespective of the pressure at said head if ithas not opened during said time delay.
 9. The system of claim 7 whereineach of said heads includes a closure member normally preventing theflow of extinguishant through the head, said head opening on thedischarge of said closure member from said head, and wherein saidcontrol means comprises a spring loaded rod connecting said fusiblemember and said closure member and adapted to move relative to saidclosure member upon the fusing of said fusible member.
 10. The system ofclaim 9 wherein said rod includes latching means adapted to latch saidclosure member to said head prior to the fusing of said fusible meansand adapted to release said closure member upon a predetermined movementof said rod.
 11. The system of claim 10 wherein said latching means isfurther adapted to latch said closure member to said head after anadditional predetermined movement of said rod in the absence of saidpredetermined minimum pressure at said head, the total movement of saidrod corresponding to said time delay.
 12. The system of claim 11 whereinsaid control means further comprises means to dampen said movement. 13.In combination, an extinguishant dispersing head for an automaticsprinkler system for protecting a building, fire responsive means forconditioning said head for opening in response to information receivedfrom a fire in said space, and control means for controlling the openingof said conditioned head in response to information received from thesystem within a predetermined time delay after the head has beenconditioned by said fire responsive means, said control meansmaintaining said head closed irrespective of information received fromsaid system if it is not opened during said time delay, said head havingan inlet adapted to be connected to a source of the extinguishant, anoutlet for spraying the extinguishant on a fire and a closure memberpositioned between said inlet and outlet for preventing extinguishantflow through said outlet, said control means comprising latch meanshaving a first deactivated condition, an activated condition and asecond deactivated condition, said control means locking said closuremember in its closed position in said head in said first deactivatedcondition, said control means automatically placing itself in saidsecond deactivated condition within a predetermined time period afterthe initiation of said activated condition, said control means in saidactivated condition controlling said closure member for openingautomatically if the extinguishant pressure in said head exceeds apredetermined minimum pressure, said control means in said seconddeactivated condition locking said closUre member in its closed positionirrespective of the extinguishant pressure in said head if the closuremember has not been opened during said activated condition, said fireresponsive means normally maintaining said control means in saiddeactivated condition and placing said control means in said activatedcondition in response to information received from a fire in said space.14. A fire protection system for buildings and the like comprising aplurality of extinguishant discharge heads located in a space to beprotected, means for connecting said heads to a source of extinguishant,fire responsive means responsive to a fire developing in said space forconditioning said heads for opening in a sequence dictated byinformation received from the fire, and pressure responsive means foropening said conditioned heads in response to the existence of apredetermined extinguishant pressure in said system within apredetermined time period after each head has been conditioned by saidfire responsive means, said pressure responsive means maintaining closedthose heads which are not opened during said time period irrespective ofthe extinguishant pressure in said system.
 15. The system as defined inclaim 14 wherein said pressure responsive means is responsive to theextinguishant pressure at each of said heads during said time delay,said pressure responsive means opening each head if the pressure isgreater than a predetermined minimum pressure during said time delay.16. The system of claim 15 wherein said fire responsive means comprisesa fusible member for each of said heads normally retaining said headclosed and responsive to a predetermined temperature for activating saidpressure responsive means and initiating said time delay.